dc395x: decrease iteration for tag_number of max_command in start_scsi()

The tag_number reaches dcb->max_command + 1 after the loop, but when
the tag_number equals dcb->max_command an error message is already
issued. The last iteration therefore appears obsolete.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Oliver Neukum <oliver@neukum.name>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>